Customize a Skin
Steps
A wiki skin can replace any template, stylesheet, script or image of the skin it is built on, with content held on the skin page itself and nothing changed on the server. The replacement applies to every page displayed with that skin. You need administration rights on the wiki, and Available Skins describes what a wiki skin is and which one an out-of-the-box wiki uses.
- Open the "Themes" section of the wiki administration, as described in Change the Skin of a Wiki.
- Click "Customize", beside the "Skin" field, to open the skin page that field names:

- Click "Edit this skin".
- Under "Overridden templates", type the path of the template to replace in the "Add a new overriding template" field (footer.vm, the footer of every page, for example), then click "Add":

- Write what that template is to produce in the "Content" field of the override that appears:

- Click "Save & View".
- Open any page displayed with that skin, and check that the part of the interface the template builds is the one you wrote:

FAQ
Which replacement is used when a template is defined more than once?
The skin takes the first one it finds, in this order: an override carrying that path under "Overridden templates"; the property of the same name under "Deprecated properties"; an attachment of the skin page named after the template, a template held in a subdirectory being attached under a name where the / is replaced by a .; and, if none of the three exists, whatever the skin named in "Base Skin" provides.
Should I use the "Deprecated properties" section?
No. Its six text areas (Style, Header, Footer, View Header, View and Edit) are kept so that skins written before the "Overridden templates" mechanism go on working, and they stay collapsed until you click the section heading:

How do I remove an override?
Open the skin page for editing, click the cross button beside the template's path, and confirm. The override leaves the skin page immediately, without waiting for a save, and the template the "Base Skin" provides is used again.